I believe you have to be at a certain point in the main questline and then use all of the dialog options and it should become available.
If you still don't know how, find the Boone's quest in this site. that would be a lot of help to you.
Looked at it. I have done all of it. Yes almost completed For the Republic part 2. If i finish it now im gonna start the quest "You`ll know when it happens"